3 patients with homozygous sickle cell disease have been treated with recombinant human erythropoietin in escalating doses weekly in an attempt to increase the percent of fetal hemoglobin in their red blood cells. The patients failed to show a response when treated with erythropoietin alone. In the second phase, patients were treated with hydroxyurea, which resulted in a two-to-threefold increase in their fetal hemoglobin. Currently, the patients are receiving recombinant erythropoietin along with continued hydroxyurea.